US President Donald Trump (L) and Russian President Vladimir Putin shake hands ahead a meeting in Helsinki. AFP

US President Donald Trump's decision to cancel talks with Russia's Vladimir Putin at the G20 summit was regrettable, the Kremlin said on Friday, while the Russian foreign ministry claimed that "domestic" issues in the US may have prompted the move.

"Is the provocation started by Kiev in this area (Azov Sea) a real reason for the cancellation? We heard that as an official version and we accepted that. Is it a real one? I believe we should look for answers in the U.S. domestic political situation," she was quoted as saying by Russian news agencies.

Photographers await the arrival of leaders at the Ezeiza International Airport. EPA

Mr Trump kicked off two days of diplomacy at the Group of 20 summit in Argentina on Friday after his abrupt decision to cancel a meeting with President Putin overshadowed the proceedings before they even started.

Mr Trump barreled into the two-day meeting by announcing via Twitter that he was canceling on Putin over Russia's seizure of Ukrainian vessels. His agenda Friday is expected to include meetings with world leaders, the signing of a revamped trade deal with Canada and Mexico, as well as a number of group activities for the gathering of rich and developing nations.

Coming into this G-20, Mr Trump faces a series of diplomatic challenges — most notably whether he can strike an agreement with Chinese President Xi Jinping to ease trade tensions.

Mr Trump on Thursday scrapped the meeting over Moscow's seizure at the weekend of three Ukrainian ships and continued detention of a group of Ukrainian sailors.

The two had been set for bilateral talks on Saturday at the G20 in Buenos Aires.

Mr Trump on Thursday scrapped the meeting over Moscow's seizure at the weekend of three Ukrainian ships and continued detention of a group of Ukrainian sailors.

The two had been set for bilateral talks on Saturday at the G20 in Buenos Aires.